Conventionally, as a substrate processing system for performing, e.g., a cleaning process on a substrate such as a semiconductor wafer (hereinafter, simply referred to as a “wafer”), there is known a batch type substrate processing system that simultaneously processes, e.g., 25 or 50 sheets of wafers as a single batch. In such a batch type substrate processing system, wafers taken out of one or two wafer containers constitutes the single batch and the single batch of wafers is transferred into various substrate processing apparatuses arranged in a processing section of the substrate processing system at one time. Then, after a series of processes are performed on the wafers, the single batch of wafers is returned back into the one or two wafer containers. A rinse process and a drying process are performed as a final process of the series of the processes performed in the processing section.
Patent Document 1, which was filed by the same applicant of the present application, describes a batch type substrate processing apparatus that performs a rinse process and a drying process consecutively. This substrate processing apparatus includes a cleaning tank and a drying chamber disposed above the cleaning tank. In the cleaning tank, the rinse process is performed by submerging a multiple number of wafers in pure water. In the drying chamber, the dry process is performed on the wafers. While the wafers lifted up from the pure water in the cleaning tank are being moved toward the drying chamber or after loaded into the drying chamber, IPA (isopropyl alcohol) vapor is discharged as a drying gas. As a result, pure water adhering on the surfaces of the wafers is substituted with IPA. Then, an N2 gas as an inert gas is discharged to the wafers, so that the IPA adhering on the surfaces of the wafers is removed by the N2 gas and, thus, the surfaces of the wafers are uniformly dried. Further, it is also described in Patent Document 1 that before the wafers are loaded into the drying chamber from the cleaning tank, a wall of the drying chamber is heated with a N2 gas of a high temperature and, then, an internal space of the drying chamber is cooled by supplying a N2 gas of a low temperature into the drying chamber. Through these processes, IPA vapor is condensed only on the surfaces of the wafers without being condensed on an inner wall surface of the drying chamber. Thus, IPA can dry the wafers efficiently and a particle level can be reduced. Even in the apparatus described in Patent Document 1, however, the particle level may become increased, though it is still within a tolerance range. As higher degree of wafer cleanness is required, there is a demand for suppressing the particle level to be stably lowered.
Patent Document 1: Japanese Patent Laid-open Publication No. 2009-253026